Hygroscopic controlling mechanism for an electric circuit



May g; i936@ W. B. HODGE HYGROSCOPIC CONTROLLING MECHANISM FOR ANELECTRIC CIRCUIT Filed Jan. l5, 1934 ZMLGS lnvenor.

WiHum B. Hodge byfaw wif/SWW ATB/s.

Patented May 19, 1936 UNITED STATES PATENT OFFICE HYGROSCOPICCONTROLLING MECHANISM FOR AN ELECTRIC CIRCUIT Application January 13,1934, Serial No. 706,574

6 Claims.

This invention relates to improvements in hygroscopic controllingmechanism for an electric circuit and is particularly adapted forcontroling mechanism for supplying moisture to the air of an enclosure.

In usual types of regulators for controlling the supply of moisture tothe air of an enclosure thermo-sensitive or hygroscopic elements areemployed to control a relay having an electric circuit of low voltagewhich in turn controls a commercial circuit of higher voltage havingmeans for actuating the valve or valves which control the supply ofmoisture delivered to the air of the enclosure.

One of the principal objects of the present invention is to provide aregulator of simple and eflicient construction embodying aninstantaneous non-sparking switch for controlling a commercial circuitcarrying a current of the usual 110 or 220 volts having means fordirectly actuating the valve or valves of the humidifying system to turnon or off the supply of moisture to the air.

Another object of the invention is to provide a regulator of thischaracter of such sensitivity and accuracy as not only to be applicableto the severe requirements of industrial service, but which may be madeof such small size as to be conveniently attached to the structure ofselfcontained electrically-motivated humidiers for non-industrialservice.

Another object of the invention is to provide a regulator of thecharacter described with manually operated means which may be employedalternatively to interrupt or resume the operation of the regulatoritself and of the apparatus controlled by it without in any Waydisturbing the adjustments or operating mechanism of the regulator orthe controlled apparatus.

Most of the relatively inexpensive regulators which are now availablefor household and other non-industrial service in general arecharacterized by sensitive elements composed oi rigid materials, such aswood, and other similarhygroscopic materials. Elements of this natureare commonly preferred for such service because of the considerableforce which they are able to generate and transmit in response tovariations in the humidity and which forces are commonly utilized forpurposes of switch or valve actuation. The movements, however, of suchelements due to their dimensional distortion in consequence of changinghumidity are relatively slow and so minute that levers, or othermultiplying means, are usualy necessary to transmit these motions toproduce the necessary actuation of the switch (Cl. ZOU-52) or valve.Certain other hygroscopic materials, such as hair, and yarns composed ofcertain textile materials, and the like, are known to respond morequickly to variations in humidity and to experience greater dimensionaldistortion by change in length than the more rigid materials. Suchflexible materials,v however, being elastic and flexible are lesscapable of generating and transmitting forces of the intensity generallyrequired for regulator actuation and are much more susceptible topermanent impairment by excessive strain. They have, therefore, beenchiefly used only in regulators of relatively expensive construction,while the cheaper forms of regulators have relied chiey upon the rigidmaterials.

The present invention comprises means of a simple and inexpensive naturefor utilizing the more sensitive flexible hygroscopic materials in suchmanner as to attain a degree of accuracy and sensitivity that is unusualin devices of simple and inexpensive construction.

My invention contemplates the employment of certain types ofinstantaneously acting switches, such as snap switches having a iiexibleresilient member subject to a distortional stress, maintaining themember in a certain predetermined position, as opened or closedposition, and which may be operated by the proper application ofpressure of comparatively small value to cause the switch to change fromits normal condition, whether open or closed, to the opposite condition.

Other instantaneously acting switches, and non-sparking switches such asMercoid switches, may also be used in connection with my invention.Switches of these types are capable of opening and closing usualcommercial one hundred ten and two hundred twenty volt circuits, so thatregulation of the humidifying device may be accomplished without the useof relays which are employed in usual types of regulators, and theelimination of such relays obviously greatly reduces the expense of theequipment.

Where the actuating element for the switch is of rigid material it isusually necessary to employ lever systems, or other equivalent means formultiplying the expansion or contraction of the hygroscopic element inorder to produce the necessary movement of the switch-operating member.It is also necessary to provide springs or other mechanical devices forabsorbing any surplus expansion or contraction of the actuating memberabove that value which produces actuation in order to avoid structuralstrains that otherwise would be caused.

Where the actuating element for the switch is of flexible hygroscopicmaterial, resilient means, such as spring mechanism, has heretofore beenemployed to relieve the strain upon the hygroscopic element produced byextreme changes in humidity beyond the point at which the regulator isset to operate, and the additional continued strain produced by thespring, after the switch has been actuated, is likely so to stretch thehygroscopic element as to cause it to lose its initial adjustmentsetting. For example, if a humidity controller is set to close anelectric contact at (S0-degrees relative humidity, thereby completingthe circuit to actuate a valve of the humidifying system, and thehumidity of the atmosphere should continue to become lower, there wouldbe an additional strain upon the hygroscopic member which would cause itso to stretch that it would lose its initial adjustment.

The tendency to stretch the hygroscopic element by continued strainproduced by the spring, when the hygroscopicI element becomes moist byhigher humidities, is more pronounced and such strain consequently morereadily causes the hygroscopic member to lose its initial adjustmentsetting.

IThe present invention avoids all necessity for the use of either ofthese compensating expedients by making use of a simple metallic weightsupported by a flexible element composed of hygroscopic material subjectto elongation in response to rising humidity and contraction in responseto falling humidity, such as gold-beaters skin, gut, or other membranousmaterial. Preferably the weight is so suspended as to be locateddirectly above the operating member of the switch. The weight hassuflicient mass when resting upon a strut or stylus engaging theoperating member of the switch, as to cause the actuation of the switchand the length of the hygroscopic element is such that its change oflength due to the permissible variation in humidity and correspondingvertical travel of the weight slightly exceeds the required verticaloperating movement that is characteristic of the switch.

By reason of the construction above described the tension imposed uponthe hygroscopic member by the weight is immediately relieved when theweight rests upon the switch or its operating member, or the casingenclosing the switch, and if the humidity continues to rise noadditional strain is imposed upon the hygroscopic member which wouldcontinue to stretch it. When, upon the other hand, the weight is raisedby the hygroscopic member out of contact with the switch or itsactuating member by reason of decrease in humidity of the air of theenclosure, the drying out of the hygroscopic member decreases itstendency to stretch, and as no additional strain is imposed upon thehydroscopic element by a spring, or otherwise, it will not be caused tolose its initial adjustment setting. It has, as a matter of fact, beenfound in actual practice that although the hygroscopic member embodyingthe present invention has been left in a quiescent state for severalmonths its operation can be resumed upon practically the same initialsetting.

The hygroscopic element must have sufficient tensile strength to supportthe weight without being strained beyond its elastic limit and suchstrength may be provided either by composing the element of multiplestrands in suflicient number or by selecting an element of the characterdescribed of sufficient width and cross sectional area to insure thenecessary strength. Because of the superior sensitivity of a hygroscopicelement of this type and the elimination of unnecessary mechanismheretofore employed, it is possible to provide a hygroscopic controllingdevice ior an electric circuit of very compact dimensions and one whichis chiefly characterized by its direct actuation of the switch by thevertical movement of a weight in the absence of multiplying andstrain-absorbing mechanism.

Where the controlling device is employed for the regulation of acommercial electric current, it is essential to the purpose of myinvention that the switch should have instantaneous actuation both inopening and closing to insure the prevention of sparking and consequentcorrosion and deterioration of the Contact surfaces which otherwisewould be unavoidable.

These and other objects and features of the invention will more fullyappear from the following description and the accompanying drawing andwill be particularly pointed out in the claims.

In the drawing:

Fig. 1 is a view, mainly in vertical section, of a preferred form of theinvention;

Fig. 2 is a detail view of an upper portion of the apparatus shown inFig. 1 in vertical section at ight angles to the section shown in Fig.l; an

Fi'g. 3 is a diagrammatic view illustrating another method of supportingthe weight upon the flexible hygroscopic element and illustrating theadvantage in the vertical movement of the weight obtained by suchconstruction.

The preferred embodiment of the invention illustrated comprises a framehaving a hollow, preferably rectangular, base l provided with endflanges 2 having suitable screw holes by means of which the same may besecured to a post wall or other support. The top of the base de-7sirably is provided with an upwardly extending annular flange 3 forminga seat for a metallic tubular member 4 which is provided with a suitableaperttue 5 to permit the passage oi air therethrough. The tubularmember' 4 encloses and provides a guide for a weight 6 which issuspended by a hygroscopic element l in a suitable support in the upperend of the tubular member, as will hereinafter' more fully appear.

An instantaneous switch adapted to be operated by the raising andlowering movements of the weight, in response to varying conditions ofhumidity, is mounted in the hollow base. The instantaneous switch may beoi any suitable tvpe for controlling a commercial electric current` ofone hundred ten or two hundred twenty volts without producing suchsparking as will cause deterioration of the elements of the switch.Desirably an instantaneous snap switch is employed. but it will bereadily understood that ahtilting Mercoid switch, a switch in which theconducting terminals are located in a Vacuum, or other types ofinstantaneous or non-sparking switches may be used.

The switch, which is illustrated in the accompanying drawing, is a snapswitch of standardized construction that is available in the openmarket, and comprises a casing or" rectangular form having a base 8 ofinsulation which is suitably secured to` the bottom of the hollow baseof the frame and rectangular vertical walls 9 which enclose terminals IUand l! for the electric circuit which is supplied through conductors IE!and !3 to the respective terminals l0 and l I. The movable switchelement comprises a iiexible resilient thin plate I4 which is xedlysecured to the terminal I I and which has been subjected to an initialdistortional stress of suflicient value normally to maintain the freeend thereof in contact with the terminal IIJ thereby to eect a normalclosure of the circuit.

The plate I4 is of such character, due to the initial stress to which itis subjected, that pressure imposed upon the plate in proximity to itsanchorage will overcome the distortional stress a-nd cause the free endof the plate to snap instantly toward open position. The amplitude ofmovement of the free end of the plate I4 may be and desirably is limitedby an insulated stop I5 which is located above the end of the plate andspaced apart from the terminal end by a block of insulating material I6.A convenient means for applying force to the plate I4 to eiect theopening movement thereof comprises a pin I1 which is slidably mounted ina boss in the insulated cover I 8 of the switch-enclosing casing, Thepin I1 is located axially beneath the weight 6.

Desirably a manually operable stop switch is interposed in the circuitleading tol the terminals of the switch and such a manually operableswitch may be conveniently mounted in the hollow base. In the particularconstruction illustrated the conductors I2 and I3 lead through suitablelaminated insulation I9 to a switch mechanism which is mounted in ascrew threaded block 2U which extends through the upper wall of thecasing and is secured thereto by upper and lower nuts 2I and 22. Asuitable handle 23 for the switch extends upwardly through the centralportion of the block 20 and may be moved laterally to open or close thestop switch.

The hygroscopic element may be of any suitable lexible material capableof producing considerable elongation and contraction in response toincreasing and decreasing humidity in the air to which it is subjected.Preferably the hygroscopic element is composed of one or more strands orribbon of animal tissue, such as gold-beaters skin or ox gut.

In the preferred construction the hygroscopic member is in the form of aloop which preferably extends beneath a sleeve 24 which is rotatablymounted upon a pin 25 the ends of which are anchored in bosses 26extending upwardly from and integral with the weight 6. The upper endsof the hygroscopic element are secured to an adjustable support locatedin the upper end of the tubular member 4.

In the preferredconstruction illustrated the upper ends of thehygroscopic member 1 are clamped to a rectangular block 21 by plates 28which are screwed to the block. The block 21 is provided near its upperend with a transverse bore 29 having a narrow slot 30 extending from thebore through the upper edge of the block. The block is suspended upon ascrew 3| having at its lower end an integral cylindrical extension orstem 32 terminating in an enlarged| spheroidal end 33 which enters thebore 29 in the block 21.

In assembling the device the stem 32 and spheroidal end may be insertedlaterally through the slot and bore as will be readily understood. Thescrew 3| extends axially through and its threads engage complementarythreads in a metallic block or head 34 which is xedly secured in theupper end of the tubular member by screws 35. The head 34 is providedwith an upwardly exthe humidifying means.

been depressed suiciently to cause the plate I4 tending annular flange36 in which an adjusting member or knob 31 is rotatably mounted andspaced apart from the head 34 by a spiral spring 38, the lower end ofwhich rests upon the head 34 and the upper end of which enters a recessin the adjusting knob 31. The screw 3| has threaded engagement with theadjusting knob 31, but is adapted to be rigidly secured thereto by aclamping screw 39, the end of which abuts against the screw 3 I.

The lower end of the adjusting knob is provided with a cut-away portionor recess 40 and a stop screw 4I extending through the flange 36 of thehead enters the recess in such manner that engagement with the shouldersat the end of the recess 40 will limit the rotative movement of theadjusting knob 31.

In the assembling of the device the clamping screw 39 is backed off topermit rotation of the screw 38. The knob 31 is then held in suchposition that the stop screw 4I is approximately midway of the length ofthe slot 40 and the screw 3I rotated to give a rough adjustment to theposition of the lower end of the weight 6 relatively to the upper end ofthe pin I1. The clamping screw 39 is then set up and furthermoreaccurate adjustment of the weight produced by rotation of the knob toposition the weight in such manner that the lowering and raising of theweight will actuate the flexible plate I4 of the snap switch to break ormake the electric circuit in response to variation of humidity of theair from a predetermined standard.

The controlling device is primarily intended for regulation ofhumidifying apparatus for supplying moisture to the air of an enclosure,the electric circuit being employed to control a solenoid, or otherelectrically operated valve for turning on or off a supply of moistureto the air of the enclosure, or t-o control a humidifier.

When in operation the regulator herein disclosed is initially adjustedfor actuation within a predetermined range or standard of humidity,rising humidity causes the hygroscopic element 1 to increase in length,whereupon pressure of the weight 6 upon the pin I1 causes the switchplate I4 to snap to open position, thereby interrupting the circuit anddiscontinuing the operation of When the pin I1 has to snap to openposition, further descent of the weight will be prevented by theresistance of the pin I1 or by the engagement of the weight with theboss upon the cover plate IB so that the strain upon the hygroscopicmember will be relieved and such stretching of the hygroscopic member,while subjected to high humidity as might otherwise cause it to lose itsinitial adjustment setting, will be avoided. Falling humidity causes thehygroscopic element 1 to contract and to lift the weight, therebyreducing the pressure applied to the actuating pin I1 until thedistortional stress and resiliency of the fiexible plate I4 will snapthe switch member to closed position, thereby completing the electriccircuit and effecting resumption of humidiication upon which the cycleof operation is resumed and a standard of humidity is maintained withinlimits corresponding to the sensitivity of the regulator. By therotation of the knob 31 in a proper direction the xed end of thehygroscopic element and the weight supported thereby may be raised orlowered to adjust the standard o-f humidity to any predetermined higheror lower degree as may be desired. The hand operated switch, which iscon- 75 nected in series with the snap switch, may be opened or closedat will by manipulation of the handle 23 to make or break the circuitwithout disturbing any of the adjustment-operating parts, or otherconnections of the controller.

In order to prevent injury to the hygroscopic element or other portionsof the device during storage and transportation, means desirably areprovided for maintaining the weight 6 in fixed position. This isconveniently accomplished by providing a set screw 42 in the post whichextends upwardly from the hollow base adapted when set up to engage theside of the Weight B and clamp it in a xed position, thereby preventingsuch movement of the weight as either would impose a tension or jerkupon the hygroscopic element or hammering of the pin which engages andactuates the movable plate I4 of the snap switch.

It will be understood that other means may be provided for supportingthe hygrosc-opic member. In Fig. 3 a modification of the invention isillustrated diagrammatically which will enable the hygroscopic elementto give a greater amplitude of vertical movement to the weight. In thisconstruction the hygroscopic element 'l is illustrated in full lines as43 and 44 normally distorted from horizontal position by the weight 6,it being understood that one or both ends are adjustably secured to asuitable support in substantially the same horizontal plane. Theposition of the hygroscopic member, when subjected to a predeterminedincrease in humidity, is illustrated by the dotted line position 45 and46 and that of the weight by the dotted line position.

A comparison of the distances through which the weight would movevertically when the hygroscopic element is, first, in vertical positionand, second, in horizontal position is illustrated by the dottedextension of the line which is located above the diagrammatic ligure.The normal length of the hygroscopic element before elongation isrepresented by the distance between the points a and b and this lengthcorresponds to the combined lengths of the halves 43 and-44 of thehygroscopic element 1 shown in the diagram. The elongation of theelement when subjected to rising humidity is illustrated by the dottedlines 45 and 46 and the length of the lines 45 and 46 when in alinementequals the distance between the points a and c. Therefore, the distancebetween the points band c represents the exact elongation of thehygroscopic element and the distance which the weight would lower undersuch conditions if the hygroscopic member and weight were suspendedvertically. However, where the hygroscopic element is supported at itsends in a horizontal plane and the weight applied centrally, as showndiagrammatically, the vertical movement of the weight is the distancebetween the points d and e. If this distance d-e is measured from thepoint b upon the line, it will be observed that the distance throughwhich the weight drops is much greater than the distance between b and cwhich is thedistance the weight drops when attached to the lower end ofa vertically suspended hygroscopic element.

It will thus be seen that an increased weightmovement is obtained byinitially positioning the hygroscopic element in horizontal position andit will be readily understood that the form of the casing and the mannerof suspending and adjusting the tension upon the hygroscopic element maybe readily made to secure the advantage of such construction by thoseskilled in the art.

It will be understood that the particular embodiment of the inventiondisclosed herein is of an illustrative character and is not restrictive,and that various changes in form, construction and arrangement of partsmay be made within the spirit and scope of the following claims.

Having thus described the invention, what is claimed as new, and desiredto be secured by Letters Patent, is:

1. A hygroscopic control for an electric circuit comprising a rigidframe, an instantaneous switch for the electric circuit mounted thereon,an hygroscopically extensible element adjustably suspended from saidframe, a Weight suspended by said element directly above the operatingmember of said switch and operable upon elongation of said member inresponse to rising humidity to cause said weight to depress saidoperating member and thereby to actuate said switch at a predeterminedcondition of humidity.

2. A hygroscopic control for an electric circuit comprising a rigidframe, supporting means adjustably mounted on said frame, a hygroscopicelement subject to elongation in response to rising humidity andcontraction in response to falling humidity suspended from saidsupporting means, a weight directly suspended upon said hygroscopicelement and acting to move vertically in accordance with elongation orcontraction thereof, a self-closing instantaneous switch mounted on saidframe below and in the path of said weight and having a conductingmember movable to open position by the action of said weight uponelongation of said element in response to humidity rising to apredetermined value.

3. A hygroscopic control for an electric circuit comprising a frame, aninstantaneous self -closing switch for said circuit mounted thereon, aweight suspended from said frame directly above the actuating member ofsaid switch upon a hygroscopically extensible element composed ofelastic material, said element being adjustably supported on said frameand having an elastic limit that exceeds the tensile strain imposedthereon by said weight, the said Weight in accordance with the extensionof said element upon humidity rising to a predetermined value beingoperable directly to actuate said switch.

4. An article of manufacture comprising a casing having a hollow base,an apertured tubular member extending vertically upwardly therefromprovided with a vertically adjustable supporting member in its upperend, an instantaneous switch mounted in said hollow base, a flexiblehygroscopic element subject to elongation in response to rising humidityand to contraction in response to falling humidity secured at its upperend to said supporting member, a weight slidably mounted in said tubularmember and guided thereby suspended by said hygroscopic element directlyabove the movable element of said switch and operable upon elongation ofsaid member in response to rising humidity to cause said weight toactuate said instantaneous switch.

5. An article of manufacture comprising a casing having a hollow base,an apertured tubular member extending vertically upwardly therefromprovided with a vertically adjustable supporting member in its upperend, an instantaneous switch mounted in said hollow base, a iiexiblehygroscopic element in the form of a loop connected at its upper end tosaid adjustable supporting member, subject to elongation in response torising humidity and to contraction in response to falling humidity,secured at its upper end to said supporting member, a weight slidablymounted in said tubular member and guided thereby suspended by saidhygroscopic element midway of its length directly above the movableelement of said switch and operable upon elongation of said member inresponse to rising humidity to cause said weight to depress saidoperating member and thereby actuate said switch at a predeterminedcondition of humidity.

6. An article of manufacture comprising a casing having a hollow base,an apertured tubular member extending vertically upwardly therefromprovided with a vertically adjustable supporting member in its upperend, an instantaneous switch mounted in said hollow base, a exiblehygrof scopic element subject to elongation in response to risinghumidity and to contraction in response to falling humidity secured atits upper end to said supporting member, a weight slidably mounted insaid tubular member and guided thereby suspended by said hygroscopicelement directly above the movable element of said switch and operableupon elongation of said member in response to rising humidity to causesaid weight to actuate said instantaneous switch, and means forrelieving said hygroscopic element from further extensional strain afterthe actuation of said switch.

WILLIAM B. HODGE.

